The initial phase of the study will focus on the synthesis of side chain allenic retinoids. In the second phase, rearrangement studies of the allens via sigmatrophic or catalyzed reactions will be pursued. Alkylated, ring-fused, and other analogs will be pursued. The 7, 8 - allens and their rearrangement reactions will be pursued in the third phase, and, finally, the 6, 7, and 10, 11 - allens. The primary goal is to systematically investigate the possibility that allenic and acetylenic groups might impart useful cancer prophylactic properties to the retinoids.